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From: Waiman Long <waiman.long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arch@vger.kernel.org,
	Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	Oleg Nesterov <oleg@redhat.com>,
	kvm@vger.kernel.org, Scott J Norton <scott.norton@hp.com>,
	x86@kernel.org, Paolo Bonzini <paolo.bonzini@gmail.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Ingo Molnar <mingo@redhat.com>,
	David Vrabel <david.vrabel@citrix.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	xen-devel@lists.xenproject.org,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Douglas Hatch <doug.hatch@hp.com>
Subject: Re: [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support
Date: Mon, 27 Oct 2014 14:00:38 -0400	[thread overview]
Message-ID: <544E8846.9030003__29192.840451333$1414432962$gmane$org@hp.com> (raw)
In-Reply-To: <20141024085659.GW21513@worktop.programming.kicks-ass.net>

On 10/24/2014 04:57 AM, Peter Zijlstra wrote:
> On Thu, Oct 16, 2014 at 02:10:29PM -0400, Waiman Long wrote:
>> v11->v12:
>>   - Based on PeterZ's version of the qspinlock patch
>>     (https://lkml.org/lkml/2014/6/15/63).
>>   - Incorporated many of the review comments from Konrad Wilk and
>>     Paolo Bonzini.
>>   - The pvqspinlock code is largely from my previous version with
>>     PeterZ's way of going from queue tail to head and his idea of
>>     using callee saved calls to KVM and XEN codes.
> Thanks for taking the time to refresh this.. I would prefer you use a
> little more of the PV techniques I outlined in my latest PV patch to
> further reduce the overhead of PV enabled kernels on real hardware.
>
> This is an important use case, because distro kernels will have to
> enable PV support while their majority of installations will be on
> physical hardware.
>
> Other than that I see no reason not to move this forward.

Thanks for reviewing the patch and agree to move forward. Currently, I 
am thinking of separating out a PV and non-PV versions of the lock 
slowpath functions as shown in my previous mail. That should also 
minimize the performance impact on bare metal even more than what can be 
done with the PV techniques used in your patch while not penalizing PV 
performance.

As for the unlock function, if the site patching function can handle all 
the possible call sites of spin_unlock() without disabling function 
inlining, I will be glad to use your way of handing unlock function. 
Otherwise, I will prefer my current approach as it is simpler and more 
easy to understand as well as similar to what has been done in the pv 
ticket spinlock code.

-Longman

  reply	other threads:[~2014-10-27 18:00 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-16 18:10 [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 01/11] qspinlock: A simple generic 4-byte queue spinlock Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 02/11] qspinlock, x86: Enable x86-64 to use " Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 03/11] qspinlock: Add pending bit Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 04/11] qspinlock: Extract out code snippets for the next patch Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 05/11] qspinlock: Optimize for smaller NR_CPUS Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 06/11] qspinlock: Use a simple write to grab the lock Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 07/11] qspinlock: Revert to test-and-set on hypervisors Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 08/11] qspinlock, x86: Rename paravirt_ticketlocks_enabled Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10   ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 09/11] pvqspinlock, x86: Add para-virtualization support Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-24  8:47   ` Peter Zijlstra
2014-10-24  8:47   ` Peter Zijlstra
2014-10-24  8:47   ` Peter Zijlstra
2014-10-24 20:53     ` Waiman Long
2014-10-24 20:53       ` Waiman Long
2014-10-24 22:04       ` Peter Zijlstra
2014-10-24 22:04         ` Peter Zijlstra
2014-10-25  4:30         ` Mike Galbraith
2014-10-25  4:30         ` Mike Galbraith
2014-10-25  4:30         ` Mike Galbraith
2014-10-27 17:15         ` Waiman Long
2014-10-27 17:15         ` Waiman Long
2014-10-27 17:15           ` Waiman Long
2014-10-27 17:27           ` Peter Zijlstra
2014-10-27 20:50             ` Waiman Long
2014-10-27 20:50             ` Waiman Long
2014-10-27 20:50               ` Waiman Long
2014-10-27 17:27           ` Peter Zijlstra
2014-10-27 17:27           ` Peter Zijlstra
2014-10-24 22:04       ` Peter Zijlstra
2014-10-24 20:53     ` Waiman Long
2014-10-24  8:54   ` Peter Zijlstra
2014-10-24  8:54     ` Peter Zijlstra
2014-10-27 17:38     ` Waiman Long
2014-10-27 17:38       ` Waiman Long
2014-10-27 18:02       ` Konrad Rzeszutek Wilk
2014-10-27 18:02         ` Konrad Rzeszutek Wilk
2014-10-27 20:55         ` Waiman Long
2014-10-27 20:55         ` Waiman Long
2014-10-27 20:55         ` Waiman Long
2014-11-26  0:33         ` Waiman Long
2014-11-26  0:33         ` Waiman Long
2014-11-26  0:33         ` Waiman Long
2014-12-01 16:51           ` Konrad Rzeszutek Wilk
2014-12-01 16:51           ` Konrad Rzeszutek Wilk
2014-12-01 16:51             ` Konrad Rzeszutek Wilk
2014-10-27 18:02       ` Konrad Rzeszutek Wilk
2014-10-27 18:04       ` Peter Zijlstra
2014-10-27 18:04       ` Peter Zijlstra
2014-10-27 18:04       ` Peter Zijlstra
2014-10-27 21:22         ` Waiman Long
2014-10-27 21:22         ` Waiman Long
2014-10-27 21:22         ` Waiman Long
2014-10-29 19:05           ` Waiman Long
2014-10-29 19:05           ` Waiman Long
2014-10-29 19:05             ` Waiman Long
2014-10-29 20:25             ` Waiman Long
2014-10-29 20:25             ` Waiman Long
2014-10-29 20:25             ` Waiman Long
2014-10-27 17:38     ` Waiman Long
2014-10-24  8:54   ` Peter Zijlstra
2014-10-16 18:10 ` [PATCH v12 10/11] pvqspinlock, x86: Enable PV qspinlock for KVM Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` [PATCH v12 11/11] pvqspinlock, x86: Enable PV qspinlock for XEN Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-16 18:10 ` Waiman Long
2014-10-24  8:57 ` [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support Peter Zijlstra
2014-10-24  8:57 ` Peter Zijlstra
2014-10-24  8:57   ` Peter Zijlstra
2014-10-27 18:00   ` Waiman Long [this message]
2014-10-27 18:00   ` Waiman Long
2014-10-27 18:00     ` Waiman Long
  -- strict thread matches above, loose matches on Subject: below --
2014-10-16 18:10 Waiman Long

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